I just checked Pioneer's BT module for their receivers. Since they support MP3 and AAC decoding in the receiver I thought they might support them natively. Nope, SBC only.

I fear that's going to almost always be the case. So you're ALACs will get decompressed into PCM and then encoded into SBC. Not as bad as turning already lossy compressed files like MP3 or AAC into a different lossy format, but as I said SBC isn't a very good codec (just really easy to implement in hardware).
Pioneer PDP-5020FD, Marantz SR6011
Axiom M5HP, VP160HP, QS8
Sony PS4, surround backs